The United Nations’ World Meteorological Organization (WMO) warned Wednesday that there’s a two-thirds likelihood that the planet will hit a key warming limit within the next five years.
In other words, by 2027 it is 66% likely that the Earth will average a temperature increase of 2.7 degrees Fahrenheit (1.5 degrees Celsius) as compared to the mid-19th century.
The 2015 Paris climate agreement set that temperature mark as a global guardrail for atmospheric warming. Countries who signed the agreement had pledged to try to prevent that from happening.
To meet that pledge, the world would have to stop emitting greenhouse gases altogether in the next half-century, according to climate scientists. Doing so would require a complete transformation in how people consume energy, involving massive—and costly—changes around the globe.
In a special 2018 U.N. report, preventing a one-degree Celsius (1.8 degrees Fahrenheit) increase could make a life-or-death difference over the next several decades for multitudes of people and ecosystems worldwide.
Rising temperatures impact water supplies, rising sea levels, animals’ habitats, smog, heat waves, flooding and droughts.
Fighting temperature increases could further mean the difference between whether the melting Antarctic could be reversible or not. It could possibly also save the world’s coral reefs from dying.
According to the Environmental Protection Agency (EPA), the health effects on U.S. residents could include respiratory and heart diseases, as well as pest-related diseases such as Lyme disease and West Nile Virus. Climate change has also been linked to violent crime and mental health, the EPA says.
In a statement WMO Secretary-General Petteri Taalas commented on the latest report, saying that it “does not mean that we will permanently exceed the 1.5 C level specified in the Paris Agreement which refers to long-term warming over many years. However, WMO is sounding the alarm that we will breach the 1.5 C level on a temporary basis with increasing frequency.”
Key to the global temperature threshold is the El Niño cycle. Three straight years of La Niña’s cooling trends have helped to restrain rising temperatures, but scientists are bracing for an upcoming strong El Niño warming trend.
UK-based climate scientist Leon Hermanson also noted that scientists generally measure climate change based on 30-year averages, rather than a single year.
He added, “We see this report as more of a barometer of how we’re getting close, because the closer you get to the threshold, the more noise bumping up and down is going to bump you over the threshold randomly.”